Method of treating wells



METHOD OF TREATING WELLS Robert M. Ebaugh, San Gabriel, Calif.

No Drawing. Application September 20, 1954, Serial No. 457,309

4 Claims. (Cl. 16636) My invention relates to a method of treating wells and the surrounding formations and relates in particular to a method of treating wells by the use of chemicals inorganic or organic or compounds as a part of the development of new wells or for the redevelopment or reconditioning of old wells, for the production of water, oil, gas, salt or sulphur. Oil wells and water wells are subjected to chemical treatment. For example, after the drilling of an oil well by use of the rotary method, the mud cake lining the hole and sealing off the formation must be removed. For this purpose a phosphate compound known as quadrafos solution is sometimes em ployed. The process known as acidizing is employed in both water and oil wells and chemicals are employed in solution singly or in mixtures, depending upon the particular condition in the well to be corrected. It will be understood that herein the term well'not only refers to the hole but also the adjacent formation from which fluids are produced.

It is an object of the invention to provide a method for the treatment of wells wherein a chemical treating agent of fluid character is subjected to the efiects of forces, shocks, fluid pulsations, velocities and pressures resulting from the firing of an explosive charge in proximity to the zone in the well to be treated, and While the treating agent is in direct contact with the parts or substances in the well with which the chemical reagent is capable of reacting, thereby producing results which are greatly superior to results accomplished by the mere use of chemicals in conjunction with swabbing or surging or back washing or pumping.

It is believed that the vastly superior results obtained by the use of the invention are due in part to the enhanced chemical reaction between the treating agent and the substances in the well which are to be treated thereby, as the result of the explosive force, shock, vibration, fluid pulsations and greater pressures effected by the exploding of a charge of explosives in the well close to the zone to be treated, to the disintegrating effects of the explosive shock and vibration and due to the driving of the fluid chemical reagent out into the formation which is in a clogged condition.

It is an object of the invention to provide a method of treating wells wherein various chemical treating agents are placed in the well, a plurality of explosive charges are lowered into the well (either before or after the placing of the treating agent in the well) and the explosive charges are then sequentially exploded so as to produce a series of explosions spaced apart in time, thereby producing a pulsating effect in the well and in the surrounding formation in addition to the effects of driving the treating agent out into the formation at greater velocities and pressures now possible and accelerating and intensifying the chemical reactions which form part of the treatment. The practice of the invention is not limited to any particular type of explosive. Those which may be used are the brizant explosives which explode by detonation, the slower burning or propellant types of I 1 United States Patent explosives or by mixtures of several types of explosives, but regardless of the type of explosive used or the manner in which it is set off, the quantity of each explosive charge is proportioned, by computation prior to the placing of the charges in the well, so that the explosive forces are kept within safe limits and injury to the well casing is avoided. In order that the simplicity and eifectiveness of the invention may be understood, the following detailed explanation of the use of the invention involving an acid reagent may be given. If the well extends into limestone formation the treating fluid may be 28% aqueous solution of hydrochloric acid in quantity sufiicient to assure that there will be an eifective content of the acid in the well and in the surrounding formation which is to be declogged. For example in a 14 inch diameter water well having a depth of about 423 feet through formations containing some limestone about 1,300 gallons of 28% hydrochloric acid may be pumped into the well relatively slowly so that the well will not be caused to boil over. Ten or twelve hours may be consumed in running the acid into the well. At the completion of this part of the work, a string of explosive charges is to be lowered into the Well on the lower end of an electric cable to a position of submergence in the acid solution in the zone which is being treated in the well. Then the explosive charges are sequentially fired so that a series of time-spaced explosions will occur in the zone in the well being treated. After withdrawal of electric cables from the well the pump may be put into operation and the pumping olf of the reaction product started. Indication of the extensive and intensive reaction which takes place may be observed from the very foamy consistency of the water which is pumped from the well for a considerable period of time after the use of the explosives in the manner described. That the limestone formation is violently reacted upon will be apparent from the appearance of small limestone particles and the formation of heavy foam resembling soap suds.

The particular well referred to in the foregoing example had been previously reconditioned by acidizing in the customary manner and with about the same amount and strength of acid as described in the foregoing, reconditioning the well to such a point that the pump could be operated for a period of seven hours against a discharge pressure of 145 lbs. before it would break suction. Redevelopment of the well by use of my new method, as described in the foregoing resulted in the opening of the formation to such an extent that it was possible to operate the pump continuously against lower pressures of 58 lbs. for 10 hours, lbs. for 8 hours, 62 lbs. for 3 hours, and lbs. for 2 hours without breaking suction.

In the practice of the invention, the manner of exploding a single charge or plurality of charges in the well is unimportant. A plurality of explosive charges, spaced so as to prevent sympathetic firing, may be connected to separate conductors of a multiple-conductor cable so that the electric fuses of the respective charges are disposed in separate electric circuits extending to the top of the well and switch means may be employed at the top of the well for sequentially energizing these circuits. Also, a plurality of charges may be provided with time delay electrical fuses of different time delay values, all of these fuses being connected to a single electrical circuit which passes through a cable to the surface of the ground. Then, the electrical energization of this single circuit will energize each of the electrical fuses but in view of the different timing of these fuses, the explosive charges will be fired or detonated consecutively to produce the pulsation effects hereinbefore described.

The foregoing example of the use of the invention makes known the essential characteristics thereof. Variations in the practice of the invention will be principally Patented July- 31, 1956- in the selection of difierent chemicals and different combinations of explosives (for the purpose of controlling deviation and maximum pressure of the explosive event or events) in accordance with the specific well conditions to be corrected. It will be perceived therefore that the invention resides not in the use of particular chemical reagents but in the novel manner of applying them so as to obtain improved results.

I claim:

1. A method of treating a well to recondition the same, comprising disposing a quantity of liquid chemical treating agent in a zone in the well and in direct contact with the parts of the well to be chemically treated, disposing in the well contiguous to said parts to be chemically treated, and submerged in the liquid in the well, a plurality of charges of explosive, each computed so as to be incapable of destruction of the wall of the well, firing one of said charges so that a shock wave will pass through said liquid chemical treating agent and said well and adjacent formation followed by a plurality of pulsations resulting from the sequential expansion and contraction of the body of gas resulting from the combustion of the explosive constituting said charge, and sequentially firing the remaining charges so that there will be a continued application of shock waves and pulsations to said treating agent, well and adjacent formation.

2. A method of treating a well to recondition the same, comprising running a quantity of liquid treating agent into a zone in the well and into direct contact with the parts of the well to be chemically treated, disposing in the well contiguous to said parts to be chemically treated, and submerged in the liquid in the well, a plurality of charges of explosive, each computed so as to be incapable of destruction of the wall of the well, firing one of said charges so that a shock wave will pass through said liquid chemical treating agent and said well and adjacent formation followed by heating of the liquid chemical treating agent to high temperature as the result of the combustion of the explosive charge and a forceful surging back and forth of the liquid treating agent in the well and adjacent formation effected by the plurality of pulsations resulting from the sequential expansion and contraction of the body of gas resulting from the combustion of the explosive constituting said charge, and sequentially firing the remaining charges so that there will be a continued application of shock waves and pulsations to said treating agent, well and adjacent formation.

3. A method of treating a well to recondition the same, comprising running a quantity of liquid treating agent into a zone in the well and into direct contact with the parts of the well to be chemically treated, disposing in the well contiguous to said parts to be chemically treated, and submerged in the liquid in the well, a plurality of charges of explosive, each computed so as to be incapable of destruction of the wall of the well, firing said charges so that shock waves will pass through said liquid chemical treating agent and said well and adjacent formation followed by heating of the liquid chemical treating agent to high temperature as the result of the combustion of the explosive charge and a forceful surging back and forth of the liquid treating agent in the well and adjacent formation effected by the plurality of pulsations resulting from the sequential expansion and contraction of the body of gas resulting from the combustion of the explosive constituting said charges, and withdrawing the treating agent and reaction products from the well.

4. A method as defined in claim 1 wherein fuses of different time delay values are connected to the respective explosive charges, and the fuses are simultaneously ignited, whereupon the different timing of the fuses effects sequential firing of the explosive charges.

References Cited in the file of this patent UNITED STATES PATENTS Re. 21,356 Pitzer Feb. 13, 1940 224,024 Mason Feb. 3, 1880 1,875,583 Fox Sept. 6, 1932 2,366,373 Voorhees -s Ian. 2, 1945 2,676,662 Ritzrnann Apr. 27, 1954 

1. A METHOD OF TREATING A WELL TO RECONDITION THE SAME, COMPRISING DISPOSING A QUANTITY OF LIQUID CHEMICAL TREATING AGENT IN A ZONE IN THE WELL AND IN DIRECT CONTACT WITH THE PARTS OF THE WELL TO BE CHEMICALLY TREATED, DISPOSING IN THE WALL CONTIGUOUS TO SAID PARTS TO BE CHEMICALLY TREATED, AND SUBMERGED IN THE LIQUID IN THE WELL, A PLURALITY OF CHARGES OF EXPLOSIVE, EACH COMPUTED SO AS TO BE INCAPABLE OF DESTRUCTION OF THE WALL OF THE WELL, FIRING ONE OF SAID CHARGES SO THAT A SHOCK WAVE WILL PASS THORUGH SAID LIQUID CHEMICAL TREATING AGENT ADN SAID WELL AND ADJACENT FORMATION FOLLOWED BY A PLURALITY OF PLUSATIONS RESULTING FROM THE SEQUENTIAL EXPANSION AND CONTRACTION OF THE BODY OF GAS RESULTING FROMTHE COMBUSTION OF THE EXPLOSIVE CONSTITUTING SAID CHARGE, AND SEQUENTIALLY FIRING THE REMAINING CHARGES SO THAT THERE WILL BE A CONTINUED APPLICATION OF SHOCK WAVES AND PULSATIONS TO SAID EATING AGENT, WELL AND ADJACENT FORMATION. 